The reversible relaxation of the shear modulus in amorphous Co-P alloys

Abstract

The shear modulus of electrodeposited amorphous CoP was measured via torsional vibrations at about 0.5 MHz after pre-annealing the samples for 20 h at 200 O C. Besides the isostructural, instantaneous change a relaxation of G was observed, which is caused by reversible structural relaxation of the material. During isothermal treatment after a change of the temperature G tends non-monotonically to the new temperature-dependent pseudoequilibrium. This means that at least two types of elementary processes with different kinetics govern the process. Following a concept proposed to explain the relaxation of defect concentrations in crystalline gold the observations presented in this paper are qualitatively described by the alternate play of production and annihilation of single, di-and tri-vacancies.

Structural relaxation and recovery of bulk and ribbon glassy Pd40Cu30Ni10P20monitored by measurements of infralow-frequency internal friction

“…[3,4] and papers cited in [11]). Thermal cycling of preannealed metallic glass shows notable reversible relaxation of the shear modulus [5], while the capability of 'irreversible' relaxation of the shear modulus can be largely recovered by quenching from the supercooled liquid state [6,7]. It is important to note a few reports indicating that high-temperature annealing results in partial [8,9] or nearly complete [10] recovery of the bending ductility at room temperature.…”